interfacing via wifi?

Technical Control System
1

I am in New Zealand and 2009 will be the first year that we have had a competition in New Zealand.
team 1138 (Eagle Engineering) came to New Zealand a few months ago (They were great thanks) and told us about the FRC competition and the new controller the cRIO. from what they said we can talk to it using wifi from a laptop. now can we control our robot from a laptop and how do we do that will we have to write a custom program to talk to it? or is there a program we are given/can download to talk to our robot and send it custom commands?

Scott.

2

Hello and welcome to Chief Delphi! We are all excited about the program in NZ and some of us just wish we could travel there to help. Instead I’ll settle for this virtual travel.

Many of the details of the new robot controller are not fully known by us, and there is a program being run where several very high-profile teams will be given beta-test samples to learn how they work and share with the rest of us. So, wait a few months for more details, and browse through these forums for some info as well.

The new RC will have 802.11 wifi capabilities, and you’ll be able to communicate with it from a laptop. I very much doubt you will be allowed to control it from a laptop, since the computing power may give a team an unfair advantage - but this won’t really be known until January 3, 2009 when the rules are released.

In the past, FIRST and the community released so-called “Default Code” which was a solid base on which any team could build their competition robot control software. Default code in past years included several high-level features, as well as basic drive and steering stuff. I am absolutely confident that similar default code will be available this year as well. Plan on customizing it for your particular robot, but much of the code you’ll need will be there for you to understand.

Hope this helps!

Don

3

thanks Don looks like we just have to wait to see what they give to these other teams.
i see what you are saying about using Laptops how you could get extra processing power.
so i guess i am just stuck waiting to see what happens just like everybody else.

Scott.

4

True, but you don’t have to just stand still. Learn a bit about LabView - you can download a 30 day version for free (for the cost of the bandwidth) and their “getting started” tutorials are easy to follow.

Also, once September 15 rolls around, and they send out the Beta test hardware, stay glued to the National Instruments forum here, that’s where I expect to see a LOT of information literally gushing out of the selected teams.

Stay warm down there while we roast in the heat. I just WISH I could attend the NZ Regional this March…

Don

5

There is some information available on the cRio.

http://decibel.ni.com/content/docs/DOC-1750

Provides a good overview and addresses the specific question regarding laptop control. Specifically, for the competition the robot will be controlled through a driver station, but a laptop will be attached to the system for use as a driver display/feedback station and for programming the cRio.

This makes perfect sense to me now, but five years ago when we were the only team in Western Canada and hadn’t see an FRC robot before it would have made none. So allow me to explain a bit…

The driver inputs… joysticks, gamepads, buttons, switches, custom-built scale models of a robot’s arm that can be moved into the desired position by the operator… pretty much anything that you can think of that might be used by a human being wanting to control a robot… will be hooked up to the driver station.

The driver station will encode the raw values of the driver inputs and send it to the robot. It will also send it to the laptop, where a “dashboard” program, either supplied by FIRST or designed by your team members, will display the data for your drive team to see.

The raw values of the inputs that are sent to the robot will be interpreted by the program you run on the robot. Working in conjunction with sensors on the robot this will allow you to control the machine. For instance in a simple application you might get press a button on the driver station that is intended to tell the robot to lift it’s arm (you control the function of this button in software, of course). This will change the vale of a bit from one to zero. The driver station will send that bit as part of a control packet to the robot. The robot might then look at limit switches on the robot to see if the arm had reached the safe limits of its travel. If it had not, then the cRio would signal a relay to activate the motor. Your software that you have written for the cRio will determine which relay and which direction is activated.

In a more complex application you might have a variable resistor hooked up to an analog port on the driver station, and the driver might twist the resistor to indicate the position you wish the arm to be in. The driver station would digitize the position of the resistor send this value to the cRio. You would have a resistor hooked up to the arm of your robot so that as the arm rotated the value of the resistor would change. Your software running on the cRio would read the value of the resistor on the robot, compare it to the value of the resistor being sent from the driver station, and send a numeric value to a speed controller to change the duty cycle of the PWM signal being output from the speed controller to the motor, thus affecting the voltage applied to the motor and making the arm (hopefully!) go to the desired position.

In both cases you can program the cRio (using the laptop and either Labview or the other supported programming languages) to send data from the robot back to the laptop for display. This comes in very helpful for debugging why your robot isn’t doing what you want it to, (maybe one resistor is hooked up backwards, or a switch is attached to the wrong digital input port) but also for your drivers during a competition. For instance this year we used a pneumatic system to shoot the ball over the overpass, but couldn’t shoot until we had enough pressure in the system. So we put a pressure sensor on our pneumatic system, digitized that value, sent it back from the robot and displayed it as a graph on our laptop in real time. The laptop could also plot pressure over time so we could monitor the recovery rate of our system from match to match… a quick way to check for air leaks.

My apologies if this was an overly pedantic description of the robot control system, but it was stuff that I didn’t really “get” until a couple weeks into my first build season.

Welcome to FRC… it’s great to have another whole country on board. You’ve come to a really, really good place.

Jason

P.S. I should also add that when you ask “will we be able to control the robot from a laptop”, or pretty much any technical question, there are always two answers… the technical answer and the “FRC legal” answer. The FRC legal answer is that, NO, you definitely will not be able to control the robot directly from a laptop. This is to make sure that all inputs are channelled through the driver station, and are thus subject to FRC’s safety overrides and field control system. The technical answer is that when you are sitting at home in the off-season you may very well come up with a way to run the robot directly from a laptop… so it is possible to get an answer that is both yes “you can do it at home” and no “you can’t do it at a competition”.

6

Jason, are you on the 2009 GDC?

The reason I ask this is that the 2009 FRC Game Manual is the only thing that gives the FRC legal answer. (Unless, of course, you count the Q&A and the Updates that are released twice a week or so–but those are simply interpretations and amendments, respectively.) We don’t have that yet, and as that is the case, only the game designers (GDC) know for sure (if even they know yet…). It’s quite possible that they will allow the robots to be run off a laptop.

However, according to the current documentation, we won’t be allowed to. This may change in January, but likely won’t.

7

Hey thanks for that Jason i think i understand it a lot better now but i guess i just have to wait until Jan to get some hands one experience build this robot and hopefully i see you in Atlanta.

Scott.

8

Ooops! I’ve been outed! Time to hide the fish.

Seriously, though, Eric makes a good point in that “FRC Legal” really does come from only three sources: The Game Manual (released on kickoff day and updated during the build season), The Q&A forum (started a day or two after kickoff, where teams can get official answers and interpretations of the rules) and the Updates (released typically twice each week during build season via e-mail and posted on the FRC website… and eventually reflected in the manual.)

And while I will, of course, defer to the rules should they say differently, I believe there are several technical reasons that will require all input to the cRio to travel through the driver station, just as all input to the previous robot controller had to travel through the Operator Interface.

Probably the most important point that occurrs to me as I type this is that FRC has a very thorough set of rules that are expected to be enforced meticulously. Based on past practice, if you are one pound overweight, or 1/16" over size, or used green wire where you were supposed to use red… you don’t compete until you have complied with the rule book. There are dozens of rules to read, and while they do change a bit from year to year, it would serve a rookie team well to read previous years’ rule books in advance of the competition season. Look here http://www.usfirst.org/community/frc/content.aspx?id=4094 to get an idea of what you’re going to be getting in January.

Jason

P.S. The “time to hide the fish” comment obliquely references two recurring themes on Chief Delphi… members (okay, one member in particular) of the Game Design Committe have been known to give very obscure and ultimately practically useless hints about the game prior to kickoff. There is also a recurring “joke” about next year’s game being a water game. No one is quite sure what, exactly, a “water game” is, and it makes for a funny joke the first couple times you see it. Chief Delphi veterans tend to groan a bit when they see it brought forward again year after year…